Advanced glycation end product (AGE) receptor 1 suppresses cell oxidant stress and activation signaling via EGF receptor

Abstract

Advanced glycation end product receptors (AGERs) play distinct functional roles in both the toxicity and disposal of advanced glycation end products (AGEs), substances that are linked to diabetes and aging. Overexpression of AGER1 in murine mesangial cells (MCs) (MC-R1) inhibited AGE-induced MAPK1,2 phosphorylation and NF-κB activity and also increased AGE degradation. The mechanism of the inhibitory effects of AGER1, upstream of MAPK, was explored in MCs and HEK293 AGER1-expressing cells. AGE-induced Ras activation was found to be linked to Shc/Grb2 complex formation and Shc phosphorylation in MCs, responses that were markedly reduced in MC-R1 cells. AGE responses also included EGF receptor (EGFR) phosphorylation in MCs or HEK293 cells, but this link was blocked in both MC-R1 and HEK293-R1 cells. Coexpression of AGER1 and EGFR in HEK293 cells decreased AGE-mediated EGFR and p44/p42 phosphorylation but not EGF-induced p44/p42 activation. AGE, S100/calgranulin, or H₂O₂ promoted MAPK phosphorylation in EGFR⁺ cells in a manner that was inhibitable by an EGFR inhibitor, AG1478. Also, in AGER1 cells, AGE-induced H₂O₂ formation and AGE- or S100-induced p44/p42 phosphorylation were suppressed, and these effects were restored by R1 siRNA. These data confirm that R1 negatively regulates AGE-mediated oxidant stress-dependent signaling via the EGFR and Shc/Grb2/Ras pathway. AGER1 could serve as a model for developing therapeutic targets against vascular and kidney disorders related to diabetes and aging.